Organometallic precursors for use in chemical phase deposition processes

ABSTRACT

An organometallic precursor is provided. The precursor corresponds in structure to Formula (I): Cp(R) n M(CO) 2 (X), wherein: M is Ru, Fe or Os; R is C 1 -C 10 -alkyl; X is C 1 -C 10 -alkyl; and n is 1, 2, 3, 4 or 5. The precursors are useful in chemical phase deposition processes, such as atomic layer deposition (ALD) and chemical vapor deposition (CVD).

This patent claims priority to U.S. provisional patent application Ser.No. 60/951,601 filed on 24 Jul. 2007. This application contains subjectmatter that is related to U.S. provisional patent application Ser. No.60/951,628, co-filed on 24 Jul. 2007. The disclosure of each of theapplications identified in this paragraph is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to organometallic precursors for use inchemical phase deposition processes such as chemical vapor deposition(CVD) or atomic layer deposition (ALD).

BACKGROUND OF THE INVENTION

Various organometallic precursors are used to form high-κ dielectricthin metal films for use in the semiconductor industry. Variousdeposition processes are used to form metal-containing films, such aschemical vapor deposition (“CVD”) or atomic layer deposition (“ALD”),also known at atomic layer epitaxy. Organometallic precursors depositedby such chemical phase deposition processes have applications innanotechnology and fabrication of semiconductor devices such ascapacitor electrodes, gate electrodes, adhesive diffusion barriers andintegrated circuits.

CVD is a chemical process whereby precursors are deposited on asubstrate to form a solid thin film. In a typical CVD process, theprecursors are passed over a substrate (wafer) within a low pressure orambient pressure reaction chamber. The precursors react and/or decomposeon the substrate surface creating a thin film of the desired material.Volatile byproducts are removed by gas flow through the reactionchamber. The deposition film thickness can be difficult to controlbecause it depends on coordination of many parameters such astemperature, pressure, gas flow volumes and uniformity, chemicaldepletion effects and time.

ALD is a chemical process similar to CVD, except the ALD processseparates the precursors during the reaction. The first precursor ispassed over the substrate producing a monolayer on the substrate. Anyexcess unreacted precursor is pumped out of the reaction chamber. Asecond precursor is then passed over the substrate and reacts with thefirst precursor, forming a monolayer of film on the substrate surface.This cycle is repeated to create a film of desired thickness. ALD filmgrowth is self-limited and based on surface reactions, creating uniformdepositions that can be controlled at the nanometer scale.

Moss J., Mol. Catal. A: Chem., 107:169-174 (1996) reports aninvestigation and characterization of metal alkyl complexes of the typeRMn(CO)₅ (R=alkyl group) and CpM(CO)₂R (Cp=η⁵-C₅H₅, M=Fe, Ru or Os), andbinuclear complexes Cp(CO)₂Ru(CH₂)₂Ru(CO)₂Cp.

Current precursors for use in chemical phase deposition display lowvolatility, poor growth control and an inability to scale up. Therefore,there is a need for improved chemical phase deposition precursors,particularly for use in ALD and CVD, which display higher thermalstability, better adhesion, higher vapor pressure and carbon freelayers.

SUMMARY OF THE INVENTION

There is now provided an organometallic precursor corresponding instructure to Formula I:

Cp(R)_(n)M(CO)₂(X)   (Formula I)

wherein:

-   M is Ru, Fe or Os;-   R is C₁-C₁₀-alkyl;-   X is C₁-C₁₀-alkyl; and-   n is 1, 2, 3, 4 or 5.

Other embodiments, including particular aspects of the embodimentssummarized above, will be evident from the detailed description thatfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical representation of thermogravimetric analysis (TGA)data demonstrating % weight vs. temperature of CpRu(Me)(CO)₂ [alsoreferred to here in as (cyclopentadienyl)ruthenium(methyl)(dicarbonyl)]under N₂ conditions.

FIG. 2 is a graphical representation of TGA data demonstratingdifferential vs. temperature of CpRu(Me)(CO)₂ under N₂ conditions.

FIG. 3 is a graphical representation of TGA data demonstrating % weightvs. temperature of CpRu(Et)(CO)₂ [also referred to here in as(cyclopentadienyl)ruthenium(ethyl)(dicarbonyl)] under N₂ conditions.

FIG. 4 is a graphical representation of TGA data demonstratingdifferential vs. temperature of CpRu(Et)(CO)₂ under N₂ conditions.

FIG. 5 is a graphical representation of TGA data demonstrating % weightvs. temperature of CpRu(Me)(CO)₂ under hydrogen conditions.

FIG. 6 is a graphical representation of TGA data demonstratingdifferential vs. temperature of CpRu(Me)(CO)₂ under hydrogen conditions.

FIG. 7 is a graphical representation of TGA data demonstrating % weightvs. temperature of CpRu(Et)(CO)₂ under hydrogen conditions.

FIG. 8 is a graphical representation of TGA data demonstratingdifferential vs. temperature of CpRu(Et)(CO)₂ under hydrogen conditions.

FIG. 9 is a graphical representation of TGA data comparing % weight (yaxis) vs. temperature (x axis) of CpRu(Me)(CO)₂ and CpRu(Et)(CO)₂ underoxygen conditions.

FIG. 10 is a graphical representation of root mean square (“RMS”)surface roughness results obtained in Example 4.

FIG. 11 is a graphical representation of X-ray photoelectronspectroscopy (XPS) data obtained from ALD (300 cycles) of CpRu(Me)(CO)₂onto a tantalum nitride wafer with air as a co-precursor.

FIG. 12 is a graphical representation of XPS data obtained from ALD (300cycles) of CpRu(Me)(CO)₂ onto a tantalum nitride wafer without air.

FIG. 13 is a vapor pressure equation table demonstrating a higher vaporpressure for CpRuMe(CO)₂[(cyclopentadienyl)ruthenium(methyl)(dicarbonyl)], CpRuEt(CO)₂[(cyclopentadienyl)ruthenium(ethyl)(dicarbonyl)], and (MeCp)Ru(Me)(CO)₂[(methylcyclopentadienyl)ruthenium(methyl)(dicarbonyl)] versus otherstandard precursors.

FIG. 14 is a graphical representation demonstrating higher vaporpressures for the precursors of FIG. 13 compared to various standardprecursors.

FIG. 15 is a scanning electron micrograph of a ruthenium film grownusing ALD of CpRu(Me)(CO)₂, 300 cycles.

FIGS. 16A, 16B and 16C are scanning electron micrograph of a rutheniumfilm grown using CpRu(Et)(CO)₂, 300 cycles.

FIG. 17 is a graphical representation of ALD growth rate of CpRuEt(CO)₂on Ta demonstrating thickness (angstroms) vs. # of cycles.

FIG. 18 is a table comparing physical data of CpRu(Me)(CO)₂ andCpRu(Et)(CO)₂.

FIG. 19 is a graphical representation of vapor pressure data comparingpressure (mtorr) (y axis) vs. temperature (C) (x axis) of CpRu(Me)(CO)₂and CpRu(Et)(CO)₂.

DETAILED DESCRIPTION OF THE INVENTION

In various aspects of the invention, organometallic precursors areprovided which are useful in chemical phase deposition processes,particularly CVD and ALD, to fowl thin metal-containing films, such asmetal or metal oxide films.

The methods of the invention are used to create, grow or form thinmetal-containing films which display high dielectric constants. Adielectric thin film as used herein refers to a thin film having a highpermittivity.

As used herein, the term “precursor” refers to an organometallicmolecule, complex and/or compound which is delivered to a substrate fordeposition to form a thin film by a chemical deposition process, such aschemical vapor deposition or atomic layer deposition.

In a particular embodiment, the precursor may be dissolved in anappropriate hydrocarbon or amine solvent. Appropriate hydrocarbonsolvents include, but are not limited to aliphatic hydrocarbons, such ashexane, heptane and nonane; aromatic hydrocarbons, such as toluene andxylene; aliphatic and cyclic ethers, such as diglyme, triglyme andtetraglyme. Examples of appropriate amine solvents include, withoutlimitation, octylamine and N,N-dimethyldodecylamine. For example, theprecursor may be dissolved in toluene to yield a 0.05 to 1M solution.

The term “Cp” refers to a cyclopentadienyl (C₅H₅) ligand which is boundto a transitional metal. As used herein, all five carbon atoms of the Cpligand are bound to the metal center in η⁵-coordination by π bonding,therefore the precursors of the invention are π complexes.

The term “alkyl” refers to a saturated hydrocarbon chain of 1 to 10carbon atoms in length, such as, but not limited to, methyl, ethyl,propyl and butyl. The alkyl group may be straight-chain orbranched-chain. For example, as used herein, propyl encompasses bothn-propyl and iso-propyl; butyl encompasses n-butyl, sec-butyl, iso-butyland tert-butyl. Further, as used herein, “Me” refers to methyl, and “Et”refers to ethyl.

The organometallic precursors of the invention have at least onemetallic center comprising a transition metal (“M”). Examples oftransition metals for use in the invention include, but are not limitedto Sc, Y, La, Ti, Nb, Ta, Mn, Re, Fe, Ru, Os, Co, Rh, Ni, Pd, Pt, Cu, Agand Au. In particular, there is one metal center and M is Ru, Os or Fe.In a further particular embodiment, M is Ru.

Therefore, in one embodiment an organometallic precursor is providedwhich corresponds in structure to Formula I:

Cp(R)_(n)M(CO)₂(X)   (Formula I)

wherein:

-   M is Ru, Fe or Os;-   R is C₁-C₁₀-alkyl;-   X is C₁-C₁₀-alkyl; and-   n is 1, 2, 3, 4 or 5.

In one aspect of the embodiment, the precursor corresponds in structureto Formula I wherein:

-   M is Ru;-   R is selected from the group consisting of methyl, ethyl, propyl and    butyl;-   X is selected from the group consisting of methyl, ethyl, propyl and    butyl; and-   n is 1, 2, 3, 4 or 5.

In another aspect of the embodiment, the precursor corresponds instructure to Formula I wherein:

-   M is Os;-   R is selected from the group consisting of methyl, ethyl, propyl and    butyl;-   X is selected from the group consisting of methyl, ethyl, propyl and    butyl; and-   n is 1, 2, 3, 4 or 5.

In another aspect of the embodiment, the precursor corresponds instructure to Formula I wherein:

-   M is Fe;-   R is selected from the group consisting of methyl, ethyl, propyl and    butyl;-   X is selected from the group consisting of methyl, ethyl, propyl and    butyl; and-   n is 1, 2, 3, 4 or 5.

In another aspect of the embodiment, the precursor corresponds instructure to Formula I, wherein:

-   X is selected from the group consisting of methyl, ethyl and propyl;-   R is selected from the group consisting of methyl, ethyl and propyl;    and-   n is 2, 3, 4, or 5.

In another aspect of the embodiment, the precursor corresponds instructure to Formula I, wherein:

-   M is Ru;-   X is methyl or ethyl;-   R is methyl or ethyl; and-   n is 1.

In another aspect of the embodiment, the precursor corresponds instructure to Formula I, wherein:

-   M is Os;-   X is methyl or ethyl;-   R is methyl or ethyl; and-   n is 1.

In another aspect of the embodiment, the precursor corresponds instructure to Formula I, wherein:

-   M is Fe;-   X is methyl or ethyl;-   R is methyl or ethyl; and-   n is 1.

In particular, the precursor corresponding in structure to Formula I, isselected from the group consisting of:

(methylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(ethylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(propylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(butylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(methylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(ethylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(propylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(butylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(methylcyclopentadienyl)iron(methyl)(dicarbonyl);

(ethylcyclopentadienyl)iron(methyl)(dicarbonyl);

(propylcyclopentadienyl)iron(methyl)(dicarbonyl);

(butylcyclopentadienyl)iron(methyl)(dicarbonyl);

(methylcyclopentadienyl)iron(ethyl)(dicarbonyl);

(ethylcyclopentadienyl)iron(ethyl)(dicarbonyl);

(propylcyclopentadienyl)iron(ethyl)(dicarbonyl);

(butylcyclopentadienyl)iron(ethyl)(dicarbonyl);

(methylcyclopentadienyl)osmium(methyl)(dicarbonyl);

(ethylcyclopentadienyl)osmium(methyl)(dicarbonyl);

(propylcyclopentadienyl)osmium(methyl)(dicarbonyl);

(butylcyclopentadienyl)osmium(methyl)(dicarbonyl);

(methylcyclopentadienyl)osmium(ethyl)(dicarbonyl);

(ethylcyclopentadienyl)osmium(ethyl)(dicarbonyl);

(propylcyclopentadienyl)osmium(ethyl)(dicarbonyl); and

(butylcyclopentadienyl)osmium(ethyl)(dicarbonyl).

It has been discovered that substitution of the Cp ring and tailoring ofthe alkyl group bonded to the metal has shown useful properties forchemical phase deposition processes such as CVD or ALD, or a hybrid ofCVD and ALD. Examples of such useful properties include higher vaporpressure (as demonstrated in FIG. 14) and greater thermal stability (asdemonstrated in FIGS. 1-9). Further, is has been discovered thataddition of the alkyl groups provides better adhesion to the substrate,and carbon free layers under ALD conditions. Though substituted-Cpprecursors have shown useful properties, it is possible to use both thesubstituted and unsubstituted Cp precursors of the present invention inchemical phase deposition processes.

Therefore, in yet another embodiment, a method of forming ametal-containing thin film by ALD is provided. The method comprisesdelivering at least one precursor to a substrate, wherein the precursorcorresponds in structure to Formula II:

Cp(R)_(n)M(CO)₂(X)   (Formula II)

wherein:

-   M is Ru, Fe or Os;-   R is C₁-C₁₀-alkyl;-   X is C₁-C₁₀-alkyl;-   n is zero, 1, 2, 3, 4 or 5.

And in another embodiment, a method of forming a metal-containing thinfilm by CVD is provided. The method comprises delivering at least oneprecursor to a substrate, wherein the precursor corresponds in structureto Formula II above.

In a particular embodiment, the precursor corresponds in structure toFormula II wherein:

-   M is Ru;-   R is methyl, ethyl, propyl or butyl;-   X is methyl, ethyl, propyl or butyl; and-   n is zero, 1 or 2.

In a particular embodiment, the precursor corresponds in structure toFormula II wherein:

-   M is Ru;-   R is methyl or ethyl;-   X is methyl or ethyl; and-   n is zero or 1.

In a particular embodiment, the precursor corresponds in structure toFormula II wherein:

-   M is Fe;-   R is methyl, ethyl, propyl or butyl;-   X is methyl, ethyl, propyl or butyl; and-   n is zero, 1 or 2.

In a particular embodiment, the precursor corresponds in structure toFormula II wherein:

-   M is Fe;-   R is methyl or ethyl;-   X is methyl or ethyl; and-   n is zero or 1.

In a particular embodiment, the precursor corresponds in structure toFormula II wherein:

-   M is Os;-   R is methyl, ethyl, propyl or butyl;-   X is methyl, ethyl, propyl or butyl; and-   n is zero, 1 or 2.

In a particular embodiment, the precursor corresponds in structure toFormula II wherein:

-   M is Os;-   R is methyl or ethyl;-   X is methyl or ethyl; and-   n is zero or 1.

In a particular embodiment of the invention, the precursor according toFormula II is selected from the group consisting of:

(cyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(cyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(cyclopentadienyl)iron(methyl)(dicarbonyl);

(cyclopentadienyl)iron(ethyl)(dicarbonyl);

(cyclopentadienyl)osmium(methyl)(dicarbonyl);

(cyclopentadienyl)osmium(ethyl)(dicarbonyl);

(methylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(ethylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(propylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(butylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(methylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(ethylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(propylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(butylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(methylcyclopentadienyl)iron(methyl)(dicarbonyl);

(ethylcyclopentadienyl)iron(methyl)(dicarbonyl);

(propylcyclopentadienyl)iron(methyl)(dicarbonyl);

(butylcyclopentadienyl)iron(methyl)(dicarbonyl);

(methylcyclopentadienyl)iron(ethyl)(dicarbonyl);

(ethylcyclopentadienyl)iron(ethyl)(dicarbonyl);

(propylcyclopentadienyl)iron(ethyl)(dicarbonyl);

(butylcyclopentadienyl)iron(ethyl)(dicarbonyl);

(methylcyclopentadienyl)osmium(methyl)(dicarbonyl);

(ethylcyclopentadienyl)osmium(methyl)(dicarbonyl);

(propylcyclopentadienyl)osmium(methyl)(dicarbonyl);

(butylcyclopentadienyl)osmium(methyl)(dicarbonyl);

(methylcyclopentadienyl)osmium(ethyl)(dicarbonyl);

(ethylcyclopentadienyl)osmium(ethyl)(dicarbonyl);

(propylcyclopentadienyl)osmium(ethyl)(dicarbonyl); and

(butylcyclopentadienyl)osmium(ethyl)(dicarbonyl).

In a further particular embodiment, the precursor according to FormulaII is selected from the group consisting of:

(cyclopentadienyl)ruthenium(methyl)(dicarbonyl);

(cyclopentadienyl)ruthenium(ethyl)(dicarbonyl);

(cyclopentadienyl)iron(methyl)(dicarbonyl);

(cyclopentadienyl)iron(ethyl)(dicarbonyl);

(cyclopentadienyl)osmium(methyl)(dicarbonyl); and

(cyclopentadienyl)osmium(ethyl)(dicarbonyl).

In a further particular embodiment, the precursor corresponding instructure to Formula II is(cyclopentadienyl)ruthenium(ethyl)(dicarbonyl).

In another embodiment, the precursor corresponds in structure to FormulaI and/or II, wherein butyl is selected from the group consisting ofn-butyl, sec-butyl, iso-butyl and tert-butyl.

In another embodiment, the precursor corresponds in structure to FormulaI and/or II, wherein propyl is selected from the group consisting ofn-propyl and iso-propyl.

The chemical phase deposition processes of the invention, such as ALDand CVD, can be used to form various metal-containing thin films, suchas metal or metal oxide films, on substrates using at least one of theorganometallic precursors according to Formula II. The film can beformed by the organometallic precursor independently or in combinationwith a co-reactant (can be referred to as co-precursor). Examples ofsuch co-reactants include, but are not limited to hydrogen, hydrogenplasma, oxygen, air, water, ammonia, hydrazine, allylhydrazine, borane,silane, ozone or any combination thereof.

In one embodiment, the at least one precursor is delivered to thesubstrate in pulses alternating with pulses of an oxygen source tocreate a metal oxide film. Examples of such oxygen sources include,without limitation, H₂O, O₂ or ozone.

A variety of substrates can be used in the methods of the presentinvention. For example, the precursors according to Formula I and/or IImay be delivered for deposition on substrates such as, but not limitedto, silicon, silicon oxide, silicon nitride, tantalum, tantalum nitride,or copper.

The ALD and CVD methods of the invention encompass various types of ALDand CVD processes such as, but not limited to, conventional processes,liquid injection processes and photo-assisted processes.

In one embodiment, conventional CVD is used to form a metal-containingthin film using at least one precursor according to Formula I and/or II.For conventional CVD processes, see for example Smith, Donald (1995).Thin-Film Deposition: Principles and Practice. McGraw-Hill.

In another embodiment, liquid injection CVD is used to form ametal-containing thin film using at least one precursor according toFormula I and/or II.

Examples of liquid injection CVD growth conditions include, but are notlimited to:

-   -   (1) Substrate temperature: 200-600° C. on Si(100)    -   (2) Evaporator temperature: about 200° C.    -   (3) Reactor pressure: about 5 mbar    -   (4) Solvent: toluene, or any solvent mentioned above    -   (5) Solution concentration: about 0.05 M    -   (6) Injection rate: about 30 cm³ hr⁻¹    -   (7) Argon flow rate: about 200 cm³ min⁻¹    -   (8) Oxygen flow rate: about 100 cm³ min⁻¹    -   (9) Run time: 10 min

In another embodiment, photo-assisted CVD is used to form ametal-containing thin film using at least one precursor according toFormula I and/or II.

In a further embodiment, conventional ALD is used to form ametal-containing thin film using at least one precursor according toFormula I and/or II. For conventional and/or pulsed injection ALDprocess see for example, George S. M., et. al. J. Phys. Chem. 1996.100:13121-13131.

In another embodiment, liquid injection ALD is used form ametal-containing thin film using at least one precursor according toFormula I and/or II, wherein at least one liquid precursor is deliveredto the reaction chamber by direct liquid injection as opposed to vapordraw by a bubbler. For liquid injection ALD process see, for example,Potter R. J., et. al. Chem. Vap. Deposition. 2005. 11(3):159.

Examples of liquid injection ALD growth conditions include, but are notlimited to:

-   -   (1) Substrate temperature: 160-300° C. on Si(100)    -   (2) Evaporator temperature: about 175° C.    -   (3) Reactor pressure: about 5 mbar    -   (4) Solvent: toluene, or any solvent mentioned above    -   (5) Solution concentration: about 0.05 M    -   (6) Injection rate: about 2.5 μl pulse⁻¹ (4 pulses cycle⁻¹)    -   (7) Inert gas flow rate: about 200 cm³ min⁻¹    -   (8) Pulse sequence (sec.) (precursor/purge/H₂O/purge): will vary        according to chamber size. Number of cycles: will vary according        to desired film thickness.

In another embodiment, photo-assisted ALD is used to form ametal-containing thin film using at least one precursor according toFormula I and/or II. For photo-assisted ALD processes see, for example,U.S. Pat. No. 4,581,249.

Thus, the organometallic precursors, according to Formula I or II,utilized in these methods may be liquid, solid, or gaseous.

Ruthenium precursors of Formula I and/or II can be made by the followingmethod:

reacting Ru₃(CO)₁₂ with 3(CpR_(n))H to yield 3Ru(CpR_(n))(CO)₂H and 6CO;

reacting 2Ru(Cp)R_(n)(CO)2H with [O] to yield Ru₂(CpR_(n))₂(CO)₄ and H₂;

reacting Ru₂(CpR_(n))₂(CO)₄ and 2NaK to yield 2K[Ru(CpR_(n))(CO)₂]; and

reacting K[Ru(CpR_(n))(CO)₂] and XBr to yield Cp(R)_(n)Ru(CO)₂(X);

wherein:

X is C₁-C₁₀-alkyl;

R is C₁-C₁₀-alkyl;

and n is 0, 1, 2, 3, 4 or 5.

Alternatively, ruthenium precursors of Formula I and/or II can be madeby the following method:

reacting Ru₃(CO)₁₂ with 3(CpR_(n))H to yield 3Ru(CpR_(n))(CO)₂H and 6CO;

reacting Ru(CpR_(n))(CO)₂H with BuLi to yield Li[Ru(CpR_(n))(CO)₂] andBuH;

reacting Li[Ru(CpR_(n))(CO)₂] with XBr to yield Ru(CpR_(n))(CO)₂X andLiBr;

wherein:

X is C₁-C₁₀-alkyl;

R is C₁-C₁₀-alkyl;

and n is 0, 1, 2, 3, 4 or 5.

The precursors and methods disclosed herein are useful in semiconductordevices and are useful for computer memory and logic applications, suchas dynamic random access memory (DRAM) and complementary metal oxidesemi-conductor (CMOS) circuitry. They are useful in many applicationssuch as capacitor electrodes, gate electrodes and as adhesive diffusionbarrier metal.

Precursors contemplated by the invention include, but are not limited tothose listed below. It will be noted that when n is zero, there is no Rsubstituent and the cyclopentadienyl ligand is therefore unsubstituted.Further, the R substituent is σ-bonded and its depiction belowrepresents that the cyclopentadienyl ligand may be substituted zero tofive times.

Precursor No M X R n 1 Ru CH₃ — 0 2 Ru CH₃ CH₃ 1 3 Ru CH₃ CH₃ 2 4 Ru CH₃CH₃ 3 5 Ru CH₃ CH₃ 4 6 Ru CH₃ CH₃ 5 7 Ru CH₃ — 0 8 Ru CH₃ C₂H₅ 1 9 RuCH₃ C₂H₅ 2 10 Ru CH₃ C₂H₅ 3 11 Ru CH₃ C₂H₅ 4 12 Ru CH₃ C₂H₅ 5 13 Ru CH₃— 0 14 Ru CH₃ propyl 1 15 Ru CH₃ propyl 2 16 Ru CH₃ propyl 3 17 Ru CH₃propyl 4 18 Ru CH₃ propyl 5 19 Ru CH₃ — 0 20 Ru CH₃ butyl 1 21 Ru CH₃butyl 2 22 Ru CH₃ butyl 3 23 Ru CH₃ butyl 4 24 Ru CH₃ butyl 5 25 Os CH₃— 0 26 Os CH₃ CH₃ 1 27 Os CH₃ CH₃ 2 28 Os CH₃ CH₃ 3 29 Os CH₃ CH₃ 4 30Os CH₃ CH₃ 5 31 Os CH₃ — 0 32 Os CH₃ C₂H₅ 1 33 Os CH₃ C₂H₅ 2 34 Os CH₃C₂H₅ 3 35 Os CH₃ C₂H₅ 4 36 Os CH₃ C₂H₅ 5 37 Os CH₃ — 0 38 Os CH₃ propyl1 39 Os CH₃ propyl 2 40 Os CH₃ propyl 3 41 Os CH₃ propyl 4 42 Os CH₃propyl 5 43 Os CH₃ — 0 44 Os CH₃ butyl 1 45 Os CH₃ butyl 2 46 Os CH₃butyl 3 47 Os CH₃ butyl 4 48 Os CH₃ butyl 5 49 Fe CH₃ — 0 50 Fe CH₃ CH₃1 51 Fe CH₃ CH₃ 2 52 Fe CH₃ CH₃ 3 53 Fe CH₃ CH₃ 4 54 Fe CH₃ CH₃ 5 55 FeCH₃ — 0 56 Fe CH₃ C₂H₅ 1 57 Fe CH₃ C₂H₅ 2 58 Fe CH₃ C₂H₅ 3 59 Fe CH₃C₂H₅ 4 60 Fe CH₃ C₂H₅ 5 61 Fe CH₃ — 0 62 Fe CH₃ propyl 1 63 Fe CH₃propyl 2 64 Fe CH₃ propyl 3 65 Fe CH₃ propyl 4 66 Fe CH₃ propyl 5 67 FeCH₃ — 0 68 Fe CH₃ butyl 1 69 Fe CH₃ butyl 2 70 Fe CH₃ butyl 3 71 Fe CH₃butyl 4 72 Fe CH₃ butyl 5 73 Ru C₂H₅ — 0 74 Ru C₂H₅ CH₃ 1 75 Ru C₂H₅ CH₃2 76 Ru C₂H₅ CH₃ 3 77 Ru C₂H₅ CH₃ 4 78 Ru C₂H₅ CH₃ 5 79 Ru C₂H₅ — 0 80Ru C₂H₅ C₂H₅ 1 81 Ru C₂H₅ C₂H₅ 2 82 Ru C₂H₅ C₂H₅ 3 83 Ru C₂H₅ C₂H₅ 4 84Ru C₂H₅ C₂H₅ 5 85 Ru C₂H₅ — 0 86 Ru C₂H₅ propyl 1 87 Ru C₂H₅ propyl 2 88Ru C₂H₅ propyl 3 89 Ru C₂H₅ propyl 4 90 Ru C₂H₅ propyl 5 91 Ru C₂H₅ — 092 Ru C₂H₅ butyl 1 93 Ru C₂H₅ butyl 2 94 Ru C₂H₅ butyl 3 95 Ru C₂H₅butyl 4 96 Ru C₂H₅ butyl 5 97 Os C₂H₅ — 0 98 Os C₂H₅ CH₃ 1 99 Os C₂H₅CH₃ 2 100 Os C₂H₅ CH₃ 3 101 Os C₂H₅ CH₃ 4 102 Os C₂H₅ CH₃ 5 103 Os C₂H₅— 0 104 Os C₂H₅ C₂H₅ 1 105 Os C₂H₅ C₂H₅ 2 106 Os C₂H₅ C₂H₅ 3 107 Os C₂H₅C₂H₅ 4 108 Os C₂H₅ C₂H₅ 5 109 Os C₂H₅ — 0 110 Os C₂H₅ propyl 1 111 OsC₂H₅ propyl 2 112 Os C₂H₅ propyl 3 113 Os C₂H₅ propyl 4 114 Os C₂H₅propyl 5 115 Os C₂H₅ — 0 116 Os C₂H₅ butyl 1 117 Os C₂H₅ butyl 2 118 OsC₂H₅ butyl 3 119 Os C₂H₅ butyl 4 120 Os C₂H₅ butyl 5 121 Fe C₂H₅ — 0 122Fe C₂H₅ CH₃ 1 123 Fe C₂H₅ CH₃ 2 124 Fe C₂H₅ CH₃ 3 125 Fe C₂H₅ CH₃ 4 126Fe C₂H₅ CH₃ 5 127 Fe C₂H₅ — 0 128 Fe C₂H₅ C₂H₅ 1 129 Fe C₂H₅ C₂H₅ 2 130Fe C₂H₅ C₂H₅ 3 131 Fe C₂H₅ C₂H₅ 4 132 Fe C₂H₅ C₂H₅ 5 133 Fe C₂H₅ — 0 134Fe C₂H₅ propyl 1 135 Fe C₂H₅ propyl 2 136 Fe C₂H₅ propyl 3 137 Fe C₂H₅propyl 4 138 Fe C₂H₅ propyl 5 139 Fe C₂H₅ — 0 140 Fe C₂H₅ butyl 1 141 FeC₂H₅ butyl 2 142 Fe C₂H₅ butyl 3 143 Fe C₂H₅ butyl 4 144 Fe C₂H₅ butyl 5145 Ru propyl — 0 146 Ru propyl CH₃ 1 147 Ru propyl CH₃ 2 148 Ru propylCH₃ 3 149 Ru propyl CH₃ 4 150 Ru propyl CH₃ 5 151 Ru propyl — 0 152 Rupropyl C₂H₅ 1 153 Ru propyl C₂H₅ 2 154 Ru propyl C₂H₅ 3 155 Ru propylC₂H₅ 4 156 Ru propyl C₂H₅ 5 157 Ru propyl — 0 158 Ru propyl isopropyl 1159 Ru propyl isopropyl 2 160 Ru propyl isopropyl 3 161 Ru propylisopropyl 4 162 Ru propyl isopropyl 5 163 Ru propyl — 0 164 Ru propyltert-butyl 1 165 Ru propyl tert-butyl 2 166 Ru propyl tert-butyl 3 167Ru propyl tert-butyl 4 168 Ru propyl tert-butyl 5 169 Os propyl — 0 170Os propyl CH₃ 1 171 Os propyl CH₃ 2 172 Os propyl CH₃ 3 173 Os propylCH₃ 4 174 Os propyl CH₃ 5 175 Os propyl — 0 176 Os propyl C₂H₅ 1 177 Ospropyl C₂H₅ 2 178 Os propyl C₂H₅ 3 179 Os propyl C₂H₅ 4 180 Os propylC₂H₅ 5 181 Os propyl — 0 182 Os propyl isopropyl 1 183 Os propylisopropyl 2 184 Os propyl isopropyl 3 185 Os propyl isopropyl 4 186 Ospropyl isopropyl 5 187 Os propyl — 0 188 Os propyl tert-butyl 1 189 Ospropyl tert-butyl 2 190 Os propyl tert-butyl 3 191 Os propyl tert-butyl4 192 Os propyl tert-butyl 5 193 Fe propyl — 0 194 Fe propyl CH₃ 1 195Fe propyl CH₃ 2 196 Fe propyl CH₃ 3 197 Fe propyl CH₃ 4 198 Fe propylCH₃ 5 199 Fe propyl — 0 200 Fe propyl C₂H₅ 1 201 Fe propyl C₂H₅ 2 202 Fepropyl C₂H₅ 3 203 Fe propyl C₂H₅ 4 204 Fe propyl C₂H₅ 5 205 Fe propyl —0 206 Fe propyl isopropyl 1 207 Fe propyl isopropyl 2 208 Fe propylisopropyl 3 209 Fe propyl isopropyl 4 210 Fe propyl isopropyl 5 211 Fepropyl — 0 212 Fe propyl tert-butyl 1 213 Fe propyl tert-butyl 2 214 Fepropyl tert-butyl 3 215 Fe propyl tert-butyl 4 216 Fe propyl tert-butyl5

Examples

The following examples are merely illustrative, and do not limit thisdisclosure in any way.

Example 1

The synthesis of Ru(η⁵-CpMe)(CO)₂Me [also referred to herein as(methylcyclopentadienyl)ruthenium(methyl)(dicarbonyl)] is demonstratedby the following two-step process.

Ru₃(CO)₁₂ (15.0 g, 23.5 mmols) was reacted with CpMeH in the normalmanner except that solution was heated for 1.5 hours instead of 1.0 hourand reaction with oxygenated heptane for 2.5 hours rather than 2.0hours. After cooling overnight, orange crystalline material (12.1 g,73%) was obtained. The solution is reduced to 100 ml and a further (1.9g, 11%) darker, crystalline material was obtained after standingovernight. Total yield 84%.

IR (hexane) 2007 m, 1968 m, 1960 s, 1940 m, 1788 s cm⁻¹; (CH₂Cl₂) 1997s, 1953 s, 1767 s cm⁻¹.

NMR (C₆D₆) ¹H δ 4.75 (m, 4H, CH), 4.54 (m, 4H, CH), 1.70 (s, 6H, CH₃);¹³C{¹H} δ 221.7 (CO), 109.2 (C), 89.4 (CMe), 88.5 (CMe), 12.6 (Me).

Next, Ru₂(η⁵-CpMe)₂(CO)₄ (20.4 g, 43.2 mmols) was dissolved in degassedTHF (˜250 ml), the solution degassed again and NaK (7 ml) was added.Solution was stirred for 5-6 hours until sample quenched in MeI showed acomplete reaction (2018, 1959 cm⁻¹). Unlike Ru₂(η⁵-Cp)₂(CO)₄ reaction,the quenched solution was pale yellow and the reduced solution was quitedark. There was no obvious precipitate. Solution makes up to ˜700 ml.Solution filtered into MeI (20 ml) with occasional shaking. Solvent wasremoved on rotavap (˜70 mm Hg) to give an oil which was dissolved inhexane (˜150 ml). Following filtration, solvent was removed on therotavap, the oil was transferred to a small flask and the residualhexane was removed at 0.5 mm Hg to give 22 g of a dark red oil.Distillation was performed twice at 58-60° C. (0.5 mm Hg) to give a paleyellow mobile oil (17.1 g, 79) of (η⁵-CpMe)Ru(Me)(CO)₂ depicted below.

Example 2

A synthesis scheme to prepare CpRu(Et)(CO)₂ [also referred to herein as(cyclopentadienyl)ruthenium(ethyl)(dicarbonyl) and depicted below] isdemonstrated below.

Ru₃(CO)₁₂+3CpH→3Ru(Cp)(CO)₂H+6CO

2Ru(Cp)(CO)₂H+[O]→Ru₂(Cp)₂(CO)₄+H₂

Ru₂(Cp)₂(CO)₄+2NaK→2K[Ru(Cp)(CO)₂]

K[Ru(Cp)(CO)₂]+EtBr→Ru(Cp)(CO)₂Et+KBr

Example 3

A further synthesis scheme and a method to prepare CpRu(Et)(CO)₂ isdemonstrated below.

Ru₃(CO)₁₂+3CpH→3Ru(Cp)(CO)₂H+6CO

Ru(Cp)(CO)₂H+BuLi→Li[Ru(Cp)(CO)₂]+BuH

Li[Ru(Cp)(CO)₂]+EtBr→Ru(Cp)(CO)₂Et+LiBr

All handling was under inert conditions. A suspension of Ru₃(CO)₁₂ (10.0g, 15.6 mmol) in dry, degassed heptane (400 ml) and crackedcyclopentadiene (20.5 g, 310 mmol) was refluxed for 1 hour. The volumewas reduced to 60 ml by distilling the solvent and unreactedcyclopentandiene in a stream of nitrogen and cooled. Dry degassedpentane (100 ml) was added followed by the dropwise addition of a hexanesolution of 1.6 M BuLi in hexane (31 ml, 50 mmol). The solution wasstirred for 1 hour and dry, degassed ethyl bromide (10.9 g 100 mmol)added dropwise. The mixture was stirred for a further 2 hours, filteredand the solvent removed in vacuo. The product was distilled up a shortVigreux column at 56° at 0.2 mmHg (9.4 g, 80%).

¹H-NMR (400 MHz, CDCl₃) ppm 5.23 (s, 5H, Cp), 1.77 (q, 2H, J=7.5 Hz,CH₂) ppm 1.37 (t, 1H, J=7.5 Hz, CH₃)

¹³C{¹H} NMR 202.4 (CO), 88.6 (Cp), 24.2 (CH₂), 10.0 (CH₃)

v(CO) (hexane) 2020, 1960 cm⁻¹

Example 4

ALD growth using CpRuMe(CO)₂ [also referred to herein as(cyclopentadienyl)ruthenium(methyl)(dicarbonyl)] and depicted below isdemonstrated by the following example.

Ruthenium thin films were deposited in a custom-built ALD reactor.Cyclopentadienyl ruthenium(methyl)dicarbonyl (CpRuMe(CO)₂) and air wereused as precursors. The ruthenium films were deposited on silicon wafersubstrates. Prior to deposition, the wafer substrates were dipped in a10% HF:water mixture for 30 seconds. The growth temperature was 300° C.The growth pressure is 250 milliTorr. The reactor is continuously purgedwith 30 seem of dry nitrogen. All the computer controlled valves in thereactor were the air operated ALD VCR valves from Cajon.

The amount of injected air was the volume trapped between the VCR gasket(a blank gasket with a 30 micron pin hole in it) and the ALD valve stem.For air at atmospheric pressure and temperature, this means thatapproximately 29 μmoles of air is pulsed into the reactor during the airinjection cycle. The pulse length of the air precursor is approximately1 second followed by a 2-5 second purge. No ruthenium was deposited whenthe air inject line was plugged.

The ruthenium was stored in a stainless steel ampoule. Attached directlyto the ampoule was an air operated ALD valve. The output of this ALDvalve was Tee'd with another ALD valve used for nitrogen injection. TheTee outlet leg was connected to a 500 cm³ stainless steel reservoir. Theoutlet of the reservoir was attached to a third ALD valve, called theinject valve, whose outlet goes directly to the reactor. Nitrogeninjection was used to build up the total pressure behind the rutheniuminject valve so that the pressure was higher than the reactor growthpressure. The injected nitrogen was accomplished using a 30 micron pinhole VCR gasket as described above for air injection. All of the valvesand ampoule were placed into an oven-like enclosure that allowed theampoule, valves, and tubing to be heated uniformly to 50° C. to 120° C.

During the ALD growth operation, the valves were sequenced in thefollowing manner. Immediately after an air injection, the rutheniumampoule ALD valve and the nitrogen inject ALD valve were both opened.The nitrogen inject valve was closed after 0.2 seconds. The rutheniumvapors and injected nitrogen were allowed to equilibrate in the 500 cm³reservoir during the air purge time (typically 2-5 seconds). After theair purge time had elapsed, the ruthenium ampoule ALD valve was closed,and after a 0.2 second wait time, the ruthenium inject valve was openedfor 0.2 seconds. The ruthenium was allowed to purge from the reactor fortypically 5 seconds. The air was then injected to start the ALD cycleall over again.

The effect of the dose of ruthenium precursor was investigated byvarying the precursor temperature from 85° C. to 110° C. The growth at85° C. is non-uniform. The growth with precursor temperature between 90°C. to 110° C. is uniform. Normal growth temperature is usually 90° C.

The total amount of cycles was 300. Results show that the depositionrate was independent of the ruthenium dose as varied through its vaporpressure, which in turn is varied through its evaporation temperature.This proves that the film growth proceeds in a self-limiting manner asis characteristic of ALD.

The films produce a featureless scanning electron micrograph as shown inFIG. 15. The resistivity of the films is 22-25 micro ohm cm. AFMspectroscopy at various cycles (50-300 cycles) shows the growth processvia island formation. See FIG. 10. XPS of the ALD grown ruthenium filmsdemonstrate the absence of carbon in the films. See FIGS. 11 and 12.

Example 5

ALD growth using CpRuMe(CO)₂ was also performed as in Example 4, exceptusing an argon purge, as opposed to nitrogen, a ruthenium pulse lengthof 1 second, an air pulse length of 1 second.

Example 6

ALD growth using CpRuEt(CO)₂ [also referred to herein as(cyclopentadienyl)ruthenium(ethyl)(dicarbonyl)] and depicted below isdemonstrated by the following example.

Ruthenium thin films were deposited in a custom-built ALD reactor.Cyclopentadienyl ruthenium(ethyl)dicarbonyl (CpRuEt(CO)₂) and air wasused as precursors. The ruthenium films were deposited on silicon wafersubstrates. Prior to deposition, the wafer substrates were dipped in a10% HF:water mixture for 30 seconds. The growth temperature was 265° C.The growth pressure was 100 milliTorr. The reactor was continuouslypurged with 10 sccm of argon. All the computer controlled valves in thereactor are the air operated ALD VCR valves from Cajon.

The amount of injected air was the volume trapped between the VCR gasket(a blank gasket with a 30 micron pin hole in it) and the ALD valvestein. For air at atmospheric pressure and temperature, this means thatapproximately 29 μmoles of air is pulsed into the reactor during the airinjection cycle. The pulse length of the air precursor is approximately2 seconds followed by a 2-5 second purge. No ruthenium was depositedwhen the air inject line was plugged.

The ruthenium was stored in a stainless steel ampoule. Attached directlyto the ampoule was an air operated ALD valve. The output of this ALDvalve was Tee'd with another ALD valve used for argon injection. The Teeoutlet leg was connected to a 500 cm³ stainless steel reservoir. Theoutlet of the reservoir was attached to a third ALD valve, called theinject valve, whose outlet goes directly to the reactor. Argon injectionwas used to build up the total pressure behind the ruthenium injectvalve so that the pressure is higher than the reactor growth pressure.The injected argon was accomplished using a 30 micron pin hole VCRgasket as described above for air injection. All of the valves andampoule were placed into an oven-like enclosure that allowed theampoule, valves, and tubing to be heated uniformly to 50° C. to 120° C.

During the ALD growth operation, the valves were sequenced in thefollowing manner. Immediately after an air injection, the rutheniumampoule ALD valve and the argon inject ALD valve were both opened. Theargon inject valve was closed after 0.2 seconds. The ruthenium vaporsand injected argon were allowed to equilibrate in the 500 cm³ reservoirduring the air purge time (typically 2-5 seconds). After the air purgetime had elapsed, the ruthenium ampoule ALD valve was closed, and aftera 0.2 second wait time, the ruthenium inject valve was opened for 2seconds. The ruthenium was allowed to purge from the reactor fortypically 5 seconds. The air was then injected to start the ALD cycleall over again.

The effect of the dose of ruthenium precursor was investigated byvarying the precursor temperature from 85° C. to 110° C. The growth at85° C. is non-uniform. The growth with precursor temperature between 90°C. to 110° C. is uniform. Normal growth temperature is usually 90° C.

The total amount of cycles was 300. Results show that the depositionrate is independent of the ruthenium dose as varied through its vaporpressure, which in turn is varied through its evaporation temperature.This proves that the film growth proceeds in a self-limiting manner asis characteristic of ALD.

FIGS. 16A, 16B and 16C display three scanning electron micrographs ofruthenium films grown using CpRuEt(CO)₂. Continuous films withresistances less than 100 mega ohm/square were grown with RMS surfaceroughness of 2.1 nm.

The process of Example 6 was repeated using the various substrates andcycles listed in the table below. Good growth was seen on metalsubstrates throughout an 800 cycle run.

cycles Substrate 200 400 600 800 Si No growth Good growth, Growth, roughGrowth, very (H-terminated) poor coverage surface rough surface SiO₂Some growth, Good growth Growth, rough Growth, very (native oxide) poorcoverage good coverage surface rough surface Ta/Cu Metal Good growthGood growth Good growth Good growth

FIG. 17 is a graphical representation of ALD growth rate of rutheniumfilms on Ta substrate using CpRuEt(CO)₂. A growth rate of 0.95Angstroms/cycle was achieved. Growth was measured by XRF and calibratedwith a thick sample measured by SEM.

All patents and publications cited herein are incorporated by referenceinto this application in their entirety.

The words “comprise”, “comprises”, and “comprising” are to beinterpreted inclusively rather than exclusively.

1. An organometallic precursor corresponding in structure to Formula I:Cp(R)_(n)M(CO)₂(X)   (Formula I) wherein: M is Ru, Fe or Os; R isC₁-C₁₀-alkyl; X is C₁-C₁₀-alkyl; and n is 1, 2, 3, 4 or
 5. 2. Theprecursor of claim 1, wherein: M is Ru; R is selected from the groupconsisting of methyl, ethyl, propyl and butyl; X is selected from thegroup consisting of methyl, ethyl, propyl and butyl; and n is 1, 2, 3, 4or
 5. 3. The precursor of claim 1, wherein: M is Os; R is selected fromthe group consisting of methyl, ethyl, propyl and butyl; X is selectedfrom the group consisting of methyl, ethyl, propyl and butyl; and n is1, 2, 3, 4 or
 5. 4. The precursor of claim 1, wherein: M is Fe; R isselected from the group consisting of methyl, ethyl, propyl and butyl; Xis selected from the group consisting of methyl, ethyl, propyl andbutyl; and n is 1, 2, 3, 4 or
 5. 5. The precursor of claim 1, wherein: Xis selected from the group consisting of methyl, ethyl and propyl; R isselected from the group consisting of methyl, ethyl and propyl; and n is2, 3, 4, or
 5. 6. The precursor of claim 1, wherein: M is Ru; X ismethyl or ethyl; R is methyl or ethyl; and n is
 1. 7. The precursor ofclaim 1, wherein: M is Os; X is methyl or ethyl; R is methyl or ethyl;and n is
 1. 8. The precursor of claim 1, wherein: M is Fe; X is methylor ethyl; R is methyl or ethyl; and n is
 1. 9. The precursor of claim 1,wherein butyl is selected from the group consisting of n-butyl,sec-butyl, iso-butyl and tert-butyl.
 10. The precursor of claim 1,wherein propyl is selected from the group consisting of n-propyl andiso-propyl.
 11. The precursor of claim 1, wherein the precursor isselected from the group consisting of(methylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);(ethylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);(propylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);(butylcyclopentadienyl)ruthenium(methyl)(dicarbonyl);(methylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);(ethylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);(propylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);(butylcyclopentadienyl)ruthenium(ethyl)(dicarbonyl);(methylcyclopentadienyl)iron(methyl)(dicarbonyl);(ethylcyclopentadienyl)iron(methyl)(dicarbonyl);(propylcyclopentadienyl)iron(methyl)(dicarbonyl);(butylcyclopentadienyl)iron(methyl)(dicarbonyl);(methylcyclopentadienyl)iron(ethyl)(dicarbonyl);(ethylcyclopentadienyl)iron(ethyl)(dicarbonyl);(propylcyclopentadienyl)iron(ethyl)(dicarbonyl);(butylcyclopentadienyl)iron(ethyl)(dicarbonyl);(methylcyclopentadienyl)osmium(methyl)(dicarbonyl);(ethylcyclopentadienyl)osmium(methyl)(dicarbonyl);(propylcyclopentadienyl)osmium(methyl)(dicarbonyl);(butylcyclopentadienyl)osmium(methyl)(dicarbonyl);(methylcyclopentadienyl)osmium(ethyl)(dicarbonyl);(ethylcyclopentadienyl)osmium(ethyl)(dicarbonyl);(propylcyclopentadienyl)osmium(ethyl)(dicarbonyl); and(butylcyclopentadienyl)osmium(ethyl)(dicarbonyl).